Process for printing means



April 13, 1943- E. BASSIST 2,316,18v

PROCESS FOR PRINTING MEANS I Original Filed Dec. 28, 1940 /5' C -e MPatented Apr. 13, 1943 PROCESS FOR PRINTING MEANS Mass, asaignor toWilliam Ellis Bassist, Brookline,

Craig Toland, trustee,

Original 372,142. Divided 1941, Serial N0.404,691

4Claims.

This invention relates to methods of making printing members and moreespecially to methods of making negatives, and'is a division ofapplication Ser. No. 372,142, filed December 28, 1940.

In making printing plates to reproduce a given subject matter, it iscustomary to form negatives of the subject matter by photographicprocedures and then dispose the negatives in contact withlight-sensitive coating materials applied on printing plate supports.Thereafter photographic light is allowed to pass through the translucentportions of the negative to harden the underlying light-sensitivecoating portions and render them grease-receptive. The coating thusexposed is covered with greasy ink and developed in the usual manner toform a positive printing plate. During photographic preparation ofnegatives, difiiculty arises, due to the fact that the characters orparts of the subject matter may be of different sizes and requiredifierent periods of exposure and difl'erent intensities of light forproper development, Also the method of photographically copying thesubject matter requires time and care, and is limited to the preparationof one negative at a time.

The principal object of the invention is to improve negatives, and toprovide a negative member which is prepared by mechanical operations, asdistinguished from a photographic method of copying, with a view toeliminating inaccuracies due to photographic copying procedures, andalso to shortening the time necessary for making a number ofphotographic negatives. A further object of the, invention is to presenta novel method of making and correcting photographic negatives, and toprovide a means for facilitating the making of printing plates. Theinvention also aims to provide a method of making negatives which isfast, accurate and easily carried out.

The nature of the invention, and its objects, will be more fullyunderstood from the following description of the drawing and discussionrelating thereto.

In the accompanying drawing:

Figure 1 is a fragmentary view in elevation illustrating a negativematerial of the invention;

Fig. 2 is a fragmentary view in elevation illustrating a step in themethod of forming a negative from a material such as that illustrated inFig. 1;

Fig. 3 is a fragmentary elevational view illustrating another step inthe method referred to;

Fig. 4 is a fragmentary elevational view of Bmkline, Mass.

application December 28, 1940, Serial No. and this application July 30,

Fig. 6 is a fragmentary elevational view iliustrating a modification ofmethod of making negatives.

In accordance with the invention, I provide a novel negative materialwhich is adapted to be made into a negative without resorting to theconventional procedure of photographically copying the subject matter.This negative material includes a base I having a coating 2 of ahydrophilic material and a second layer of water-soluble materialassociated with and overlying the hydrophilic material.

The base i is translucent and preferably is composed of a flexiblematerial which will resist stretching or shrinking. One example of asuitable substance is a translucent paper impregnated with waterproofingmaterials such as water-repellent resins. Other suitable substances areglass, translucent films and the like.

In the preferred impregnated paper form of base, the hydrophilicmaterial I may be partly impregnated therein and may overlie the base inthe form of a coating. By the term hydrophilic material," I mean asubstance which will absorb water, and in swollen thereby, and yet willnot dissolve away in'water. One example of a hydrophilic material, ofthe type referred to, is a coating of a instance polyvinyl alcohol andthe like. The coating or hydrophilic colloidal body 2 may in some casesinclude a hardening agent as a chromic salt.

The water-soluble material 3 is partly impregnated in and overlies thecoating at one side of the base and consists of some suitable strength,such as a film obtained from an aqueous suspension of gum arabic of aten percent solution strength. The film of gum arabic, by reason of itsbeing partly impregnated in the coating 2 presents a novel combinationof a water-soluble body, which is itself absorbent, absorbed in awater-insoluble or hydrophilic material. In addition, the gum arabicfilm aiiords a writing surface which readily accepts and holds eithergreasy ink or aqueous mixtures, which is absorbent with respect to suchmaterials, and which may be readiiy dissolved away in water.

Upon the material M, subject matter, as for example typeset subiectmatter, is printed with some instances become of a film of gum arabic ofa' light-sensitive colloid, such as bichromated albumin, and an opaquematerial, such as a dye,

is applied over the entire surface of the plate. Since thelight-sensitive, coating has a water base, it is rejected in all partsof the plate surface covered by the greasy ink image 4. As a result, acoating 5 is applied to the surface of the gum arabic around the rintingcharacters as shown in Fig. 3.

The coating 5 of light-sensitive colloid is partly absorbed into thehydrophilic material 2 and the overlyin film of gum arabic 3, and whendryexposed to photographic light. This hardens the light-sensitivecolloid and dye coating in the hydrophilic material and the gum arabic,and renders such portions completely opaque. The plate ma then be washedunder running water and lightly rubbed over with a pad or soft material.By this procedure water is allowed to penetrate into those portions ofthe gum coating directly under the greasy image 4. Such portions of thegum are dissolved away down to the layer of hydrophilic material 2 andthus throw oi! the greasy image 4. The remaining layer of hydrophilicmaterial 2 is translucent, together with the base upon which it ismounted, and there is obtained a true negative of the typeset subjectmatter made up of the parts 6 which include the photo- .graphicallyexposed albumin, gum, hydrophilic material and dye.

An important feature of the invention is the combination of the gumarabic film with a hydrophilic coating on a translucent support.

The layer of sum arabic 3 provides a surface which will readily acceptand accurately hold lines, or other forms or subject matter, or bothgreasy ink and aqueous suspensions or. mixtures. This allows a greasyimage to be applied, and thereafter a coating of bichromated albumin tobe brought into abutting relation to the greasy image without either ofthe materials tending to crawl or lose their sharpness of outline. Thecombination of a material such as the dye with a light-sensitive colloidcoating employing a chromic salt as the light-sensitizing agent allowsthe formation of hardened grease-receptive portions which are opaque.This broadens the function of light-sensitive salts of this nature andmakes possible an eflicient method of makin negatives.

The film of gum arabic dissolves in water and applied greasy image.

washes away in the same manneras the unexposed parts of a colloidcoating are washed away during conventional development or alithographic printing plate. This allows removal of the greasy imagefirst applied. In addition the film of gum arabic is characterized by acertain degree of softness which provides for the film being easilywashed away, and the ink image referred to rubbed off, without formationof ragged edges at those points where the gum is hardened in theprinting p rtions of the plate. This is highly important in insuringsharpness of outline.

The gum arabic also tends to become'impregnated in the hydrophiliccoating 2, and is further important in serving as an absorptive bodythrough which ammonium bichromate and albumin may readily pass to strikeinto the ihydro philic coating. This provides for the hydrophiliccoating, the gum, and the bichromated albumin arabic layer 3. Thepolyvinyl alcohol is of such.

character that when the bichromated albumin is coated over the surfaceof the plate around the greasy ink image already applied thereto, this"material does not diffuse or spread out but is held in the polyvinylalcohol layer with sharp outlines corresponding to the outline of thefirst This allows a true size of line or other subject matter, to bemaintained all the way down to the alcohol layer so that when the gumlayers in the parts underlying the greasy ink image are washed away, asurface of the alcohol layer 2 is exposed which conforms exactly to theoutline of the greasy ink image originally disposed on the gum arabiclayer. The hydrophilic material also serves as an excellent bondingmedium for holding the gum arabic film on the base I The negative thusprepared is of improved character. Small and large characters for agiven typeset subject matter are reproduced with equal strength andclearness, and no photographic loss or error occurs since the entireproceeding is a contact operation.

The procedure of processing the plate material M after the subjectmatter has been printed thereon, is a relatively simple one,'requiringonly a short period of time and resembling closely the commercialdevelopment of a lithographic printeflicient procedure is to provide alarge num-' ber of negatives which may be mounted on a master plate sothat a relatively small number of sheets may be ordered and printed andthereafter cut to produce the required number of sheets of the sizenoted. For instance, if sixteen photographic negatives can be quicklyprepared, they may be mounted on a master plate of a size such as 22" x34", which is an available press plate size. With such a plate, 6,250separate sheets are printed. Each sheet may thereafter be cut to formsixteen sheets of the required sizeof 5 /2" x 8 This operation ofprinting the 6,250 sheets is much more efficient than the process ofprinting 100,000 sheets of the desired size.

The sixteen negatives required in the example just describedmay bereadily prepared by the method of the invention since sixteenimpressions of the subject matter may be printed almost effected incarrying out the submarine, process for making printing plates. Theprincipal feature of the submarine process is the preparation of plateswith printing portions consisting of bichromated albumin which issoftened by the.

operation is expensive and time-consuming, and

has resulted in the discontinuance of the submarine process in mostlithographic work.

The negative ofthe invention may be coated over its entire surface withthe light-sensitive coating material. The coating isexposed withconventional color separation negatives to form opaque portions. Thesoft gum arabic 3 allows the opaque portionsto be corrected, inaccordance with the method of the submarine process, by washing whileimmersed in water. The negative thus formed may be immediately dried andemployed .in a vacuum frame or any photographic composing machine. As aresult, the excellent quality and accuracy of blended color reproductionobtainable from the corrective procedures of the submarine process maytherefore be effectively utilized by means of the negative member of theinvention. 7 1 I Various changes in the handling and application of theinvention may be resorted to. For example, instead of utilizing anopaque material, as dye, in the light-sensitive coating, I may employother opaque substances as carbon black and the like. I may alsodispense with the dye material. In this case the photographicallyhardened parts of bichromated albumin are covered with an opaque greasyink 1 before the ink image 4 and the underlying gum portions "are washedaway. A developed plate of this character is illustrated in Fig. 6 ofthe drawing.

Still other changes maybe resorted to, as for instance I may apply thelight-sensitive coating and opaque material by apparatus such as an airbrush, or by stippling, or in other ways. Similarly, variousmodifications may be resortedto in connection with the material usedforthe base, and the hydrophilic translucent coating on the base, incombination with the film of water-soluble gum arable. Otherlight-sensitive coatings such as mixtures of chromic salts and casein,glue, polyvinyl alcohol, and other similar substances, may be utilized.The steps noted may also be employed to form a planographic printingplate with the photographically hardened areas constitutinggrease-receptive printing portions.

It will be seen that I have provided an improved photographic negative'in which accuracy and uniformity of greatly enhanced character areattained. A method of making negatives quickly and cheaply is madeavailable. particularly of negatives for handling printing orders ofconsiderable volume. Various improvements and savings in connection withmaking printing plates are also made available by the use of thenegative and its treatment during. processing.

While I have shown a preferred embodiment of the invention, it should beunderstood that various changes and modifications may be resorted to inkeeping with the spirit of the invention. Having described my invention,I claim:

1. That improvement in methods of making photographic negatives whichcomprises applying a greasy image on a translucent base which includes asubstratum of a hydrophilic polyvinyl alcohol and a coating of gumarabic verlying and impregnated in the substratum, coating an opaquelight-sensitive material on the base in those areas which occurintermediate the greasy image, said light-sensitive material consistingof acolloid and a chromium compound adapted to render the colloidwater-insoluble upon exposure to actinic light, exposing thelight-sensitive material to actinic light and then removing the greasyimage.

2. That improvement in methods of making photographic negatives whichcomprises providing a translucent base which is covered at one sidethereof with a substratum of a. hydrophilic polyvinyl alcohol and alayer of gum arabic applied over the substratum of polyvinyl alcohol,applying a greasy image on the surface of the gum arabic layer, coatingan aqueous light-sensitive mixture which includes a chromium compound onthe layer of gum arabic in those areas whichoccur intermediate thegreasy image, drying and exposing the light-sensitive mixture to actiniclight, and then washing in water to remove the greasy image and portionsof the gum arabic layer occurring immediately below the greasy image.

3. That improvement in methods of making photographic negatives whichcomprises providadapted to producing a relatively large number ing atranslucent paper base which 1 includes a substratum of a hydrophilicpolyvinyl alcohol and a layer of gum arabic overlying and impregnated inthe polyvinyl alcohol, applying a reasy material on the polyvinylalcohol and gum arabic base in the form of a sharply defined image. thencoating an aqueous opaque mixture of albumin and ammonium dichromate onthe polyvinyl alcohol and gum arabic in those areas which occurintermediate the Greasy image, drying and exposing the albumin mixtureto actinic light, thereby to render the mixture insoluble in water andthen washing in water to remove the greasy image and those portions ofthe gum arabic occurring directly below the greasy image. a

4. That improvement in methods of making a printing member whichcomprises applying a greasy image on a translucent base whichincludes alayer of hydrophflic polyvinyl alcohol.

and gum arabic coated over the polyvinyl alcohol, applying an opaqueaqueous mixture of a colloid and a chromium compound, drying andexposing the colloid mixture to actinic light and then dissolving thegreasy image and the gum arable underlying the greasy image while thebase is immersed in water.

ELLIS M85181.

